Several people have asked me to explain how the examiner
determines the Writing Test score. This page should answer that question.
However, the grading for the Writing Test has changed a little since I was an
examiner so some things on this page are just my estimation of how the examiners
grade the writing today. The two official "Writing Band Descriptors"
shown below are from
2005 and I believe these haven't changed since then, but the "Score Sheet" is my
guess at what happens now.

First, the examiners gives a separate grade for each of
Task 1 and Task 2, using the "Band Descriptors" that are shown below.

They calculate the score for each Task by getting the
average score of the following four items:

1) Task Achievement (for Task 1) or Task Response (for
Task 2)

2) Coherence & Cohesion

3) Lexical Resource (= vocabulary) and,

4) Grammatical Range and Accuracy.

I am guessing that if the average score is a ".25" or a
".75" number, the examiner then goes down to the nearest ".0"
or ".5" number.

For example:

Task Achievement

7

Coherence & Cohesion

6

Vocabulary

6

Grammar

6

Average = 6.25 => 6.0

Task Achievement

6

Coherence & Cohesion

7

Vocabulary

7

Grammar

7

Average = 6.75 => 6.5

Then the examiners use a "Score Sheet" that blends the
score for the Task 1 with the score for the Task 2 to give a final Writing
Test score. On this score sheet, the Task 2 score is given more weighting
than the Task 1 score.